General Hydroponics Ca Mg Plus CaMg Plus is derived from all natural sources, not calcium nitrate. It must be added in conjunction to make calcium available to plants grown hydroponically. Calcium is an essential element that plants use to building strong healthy cell walls. Thus, it also promotes disease resistance. In general, it is a great supplement containing additional minerals necessary for structure. MSRP: $49.98 General hydroponics camg+ gallon (4/case) 726822
